Heat 2 inches of oil in a large high-sided saute pan over medium heat until it reaches 350 degrees F on a deep-fry thermometer. Add the tortilla strips in batches and fry until just crisp, about 20 seconds. Remove with a slotted spoon to a plate lined with paper towels and season with salt. Set aside.
Heat 2 tablespoons of the oil in a large saute pan over high heat. Add the garlic and mushrooms and cook until golden brown. Season with salt and pepper, to taste.
In a medium saucepan over medium heat, add the remaining oil and onion, cooking until soft. Add 4 cups of the stock and bring to a boil. Slowly add the cornmeal, whisking constantly, and continue to whisk until thickened. Reduce the heat to medium-low and cook until the grits are soft stirring constantly, adding more stock if needed, about 10 minutes. Reduce heat to low and stir in the mascarpone, season with salt and pepper, to taste, and then stir in mushrooms. Remove from heat.
Serrano Chile Sauce:
Heat the oil in a medium saucepan over high heat. Add the onion and Serrano chiles and cook until soft. Add the garlic and cook for 1 minute. Add the cream, wine and vinegar and cook until reduced by a third. Transfer the mixture to a blender, add the spinach, honey, salt and pepper and blend until smooth.
Bring water and vinegar to a simmer in high-sided saute pan. Break the eggs, 1 at a time, into a ramekin and carefully slide the egg into the simmering water, repeat with remaining eggs. Cook about 3 minutes until whites have firmed up but yolk is still soft. Remove with a slotted spoon to a plate lined with paper towels and season with salt and pepper, to taste. Serve immediately.
To plate: Spoon some of the grits into a shallow bowl, top with a poached egg. Drizzle with some of the Serrano Chile Sauce, top with some tortilla strips, sprinkle with grated cotija and garnish with cilantro. Repeat with remaining ingredients.